In order to prevent decay of wood and timbers, and thereby increase their life, it is common practice to impregnate the wood or timbers with a preservative such as creosote, mixtures of inorganic compounds which are dissolved or dispersed in water, or certain organic compounds which are dissolved in petroleum distillates or dispersed in water. The protection afforded by the application of these materials is dependent upon deep and reasonably uniform penetration of the wood or timber by the preservative material. Wood preservatives such as those described above have been applied to the wood as solutions, emulsions, pastes or dispersions in liquid hydrocarbons and/or aqueous systems. In many applications, the use of aqueous systems is preferred over liquid hydrocarbons because of the odors, flammability and often toxic nature of the liquid hydrocarbons. In some instances, the use of liquid hydrocarbons for preparing wood-impregnated solutions may result in the deposit an oily surface on the wood which is difficult to paint. Also, liquid hydrocarbons are flammable materials requiring special handling and safety precautions which add to the cost of the wood treatment.
Wood treated with organic preservatives dissolved in petroleum distillates have the same disadvantages as wood treated with hydrocarbons. Using low boiling petroleum distillates, such as mineral spirits, as solvents, fails to eliminate the disadvantages completely. Prolonged air seasoning after treatment frequently is required to permit sufficient evaporation of the solvent if the wood is to be painted. During this period of air seasoning, a portion of the preservative can migrate to the surface of the wood with the solvent, and thus, the retention of the preservative in the wood may be reduced below that contemplated for the treatment.
U.S. Pat. No. 2,423,619 describes the preparation of aqueous ammonia solutions of copper soaps by reaction of copper hydroxide or copper carbonate with naphthenic acid in the presence of ammonia.
U.S. Pat. No. 4,507,152 describes aqueous compositions having fungicidal and insecticidal properties which can be used in the treatment of wood. The aqueous compositions comprise oil-soluble metal salts of carboxylic acids, halopyridyl phosphates and surfactants. Aqueous ammoniacal solutions of fatty acid salts are described in U.S. Pat. No. 4,001,400, and aqueous solutions of metal salts of carboxylic acids and ammonia and/or ammonium compounds are described in U.S. Pat. No. 4,193,993 (Re 31,576). The ammonia and/or ammonium compounds are utilized to maintain the metal salt in solution.
Suzuki (U.S. Pat. No. 4,324,797) describes water-soluble metal soap compositions comprising the combination of a metal soap of the general formula (RCOO)xM wherein M is lithium or a non-alkali metal atom, x represents its valency, and R represents a hydrocarbon group having from 4 to 20 carbon atoms, and a chelating agent such as polybasic carboxylic acids, polyamino carboxylic acid salts, amines, etc. Conventional surfactants may be added to the aqueous solutions of the metal soap compositions. Among the amines disclosed as being useful chelating agents are polyamines such as ethylene diamine, alkanol amines such as triethanolamine, monoethanolamine, etc. Water-soluble metal soap compositions are obtained by preparing a mixture of the metal soap and the chelating agent and then heating the mixture to form the water-soluble composition.
U.S. Pat. No. 2,364,391 describes the preparation of metallic soaps useful for treating fabrics wherein metal soaps such as copper naphthenate, zinc naphthenate, etc., are complexed with ammonia and small amounts of alkanol amines are added to the ammonia complex. Examples of alkanol amines include mono-, di- and triethanol amine, and monoisopropanol amine. The alkanol amine is added to the treating solution to delay the precipitation of the soap which otherwise results when the ammonia evaporates. U.S. Pat. No. 3,262,846 describes oil-soluble copper salts emulsified in water. Diverse materials are disclosed as being useful as emulsifiers, and among the emulsifiers disclosed are the ethanolamines.
Hydrocarbon-soluble, water-insoluble salts such as copper naphthenates are described in U.S. Pat. No. 2,075,230. The hydrocarbon-soluble salts are obtained by reacting an organic acid or alkali metal salts of organic acids with a base metal compound capable of forming water-insoluble salts with said acids. Thus, the base metal compounds may be oxides or hydroxides of alkaline earth metals or heavy metals. The reaction is carried out in the presence of amines, and a wide variety of amines are disclosed as being useful. Alkylol amines such as mono-, di- and triethanolamines or propanol amines are described as being useful amines.
It also is desirable to produce wood products that are aesthetically acceptable, yet protected from wood-destroying organisms. Wood that is colored and preserved is desirable for the home, and can be used in siding, fencing and decking. Unfortunately, many of the preservative solutions used heretofore to preserve wood from wood-destroying organisms impart their own color to the wood. In many cases, the coloration imparted by the preserving solution is less than aesthetically pleasing. As mentioned above, attempts to impart desirable color by painting preserved wood often is unacceptable because it is often difficult for paint or stain to adhere to the wood and/or penetrate the oily residue left behind from the preservative treatment. Also, when wood is painted or stained to impart a desirable color, the coloration is only imparted at the surface of the wood resulting in limited permanence to weathering, scratching or wear.